Share variable between two services with two different client call

Question

I want to share a variable between two services when calling two client proxies. (And also variable should be shared per session) My sample code as below,

** Server **

Service 1

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class MyService : IMyService
{
    public string SharedValue = string.Empty;

    public void SETValue(string inputString)
    {
        SharedValue = inputString;
    }
}

[ServiceContract(SessionMode = SessionMode.Required)]
public interface IMyService
{
    [OperationContract(IsOneWay = true)]
    void SETValue(string inputString);
}

Service 2

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class MyService2 : MyService, IMyService2
{
    public string GETSharedValue()
    {
        return base.SharedValue;   //This value got Empty
    }
}

[ServiceContract(SessionMode = SessionMode.Required)]
public interface IMyService2
{
    [OperationContract]
    string GETSharedValue();
}

I'm using 'wsHttpBinding' for both services.

** Client **

    private string sharedValue = string.Empty;
    MyServiceReference.MyServiceClient client = null;
    MyService2Reference.MyService2Client client2 = null;

    public Form1()
    {
        InitializeComponent();

        client = new MyServiceReference.MyServiceClient();
        client2 = new MyService2Reference.MyService2Client();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        client.SETValue("Hello this is client 1");

        sharedValue = client2.GETSharedValue();
        lblResult.Text = sharedValue;
    }

Answer 1

write a class with a static variable eg:

public static class  SharedValues

    { 
       public static String SharedValue = string.Empty;
    }

then use

 public void SETValue(string inputString)
    {
        SharedValues.SharedValue = inputString;
    }

if you want concurrency cosider using a lock statement